• Late-planted soybeans emerge closer to the photoperiod, the event that triggers flowering and slow down vegetative growth resulting in shorter soybeans.
• Short soybeans have fewer axillary buds for pods to develop.
• Depending on the soybean maturity to be planted, increasing plant population by 10-15% can compensate for short soybeans, ultimately increasing the number of pods produced per acre.
• Narrow rows (7.5-15”) and higher populations ensure row closure, increase photosynthetic activity per acre, decrease weed competition and conserves soil moisture.
• Changing maturities may be unnecessary and is counterproductive to maximizing yield.

Increasing planting populations, to a certain extent, can incrementally help counter the effects of late planting. Unlike corn, which typically produces an ear at a single node, soybean yield capabilities are spread across axillary buds found at each leaf node.As planting date is delayed, soybean emergence occurs closer to the photoperiod (length of light and dark hours in a 24-hour period) which signals the plant to slow vegetative growth and start flowering.Unlike corn which transitions to reproductive growth after VT (tassel), vegetative and reproductive growth stages coexist in soybeans.

The slowing of vegetative growth and first flower occurs somewhere between June 15^th -20^th, depending on soybean maturity. This makes late soybeans, planted closer to this date, shorter in total height due to the little time between emergence and the start of reproductive growth (R1-first flower at any node). Shorter soybeans have fewer axillary buds at nodes, resulting in fewer potential pods per acre.Increasing planting populations is a way to counteract this by increasing the number of emerged plants per acre thus the number of soybean nodes per acre.The maturity of the variety has some impact on how great this population increase should be.In simplified terms an early variety planted late will have less time before 1^st flower (R1) than a full season variety. In this situation, increasing the planting rate by 10-15% after June 1^st for full season to early season soybeans can help minimize the effect that short soybeans (due to late planting) can have on yields.Another way to counteract the effects of late planting is by adjusting row width. While planting in narrow rows may not be possible for all farming operations, doing so has multiple advantages.First and foremost it optimizes the captured sunlight per acre thus maximizing photosynthetic activity.Narrow rows also help decrease the likelihood of weed competition and evaporative soil moisture loss.Row widths of 7.5-15 inch are sufficient to accomplish this task.

In late planting seasons, the temptation always exists to switch to an earlier maturing soybean variety.However, if the original soybean maturities chosen were appropriate for your location, this is unnecessary and can come at the cost of final yield. Late-planted soybeans will mature extremely close to the time they would have if they had been planted at normal planting dates.Once again, this is due to soybeans being photoperiod sensitive and the number of dark hours in a twenty-four-hour period that trigger R7 to R8 (beginning of full maturity) remaining the same regardless of planting date.If you absolutely must change the maturity of your variety, only slight change of 0.5 day should be made to minimize yield loss.

For more information and advice on this topic contact your local FS Crop Specialist.